How antibody works and inactivate antigens? Antigen - Antibody interaction

Each
antibody is designed for interacting with a specific antigen. Antigen-antibody
binding involves electrostatic forces, van der wall forces, hydrogen bonding
and hydrophobic interactions rather than co-valent bonds. The binding occurs
between the epitope or antigenic determinant of the antigen and paratope or
variable regions, precisely hypervariable regions of heavy and light
immunoglobulin chains.

Neutralization:
Mainly antigens like toxins of bacteria, virus, snake venom etc are neutralized
by antigen and make them ineffective. Such types of antibodies are often called
as antitoxins. Phagocytes will clear out the neutralised antigen-antibody
complexes.

Opsonisation- enhancing phagocytosis by macrophages

Opsonisation: Here we should know 2 terms clearly. First one is opsonin which refers to any
substance (eg: an antibody or c3b) that promotes phagocytosis of antigens by
binding to them. The process of enhancing phagocytosis is called as
opsonisation.In opsonisation by antibodies, antibodies will
cover or form a coat over the entire antigen surface (microbe), thereby
promoting a stable adhesive contact with an appropriate phagocytic cell and thus
making them more susceptible to phagocytosis. Antibodies involved in promoting
phagocytosis are called as opsonins.

Agglutination: Here antigens especially bacteria are made into sticky masses or clumps by the activity of antibody. Thus the antigens are immobilized and phagocytes will dispose of such clumped antigens easily. Antibodies involved in causing agglutination of antigens are often termed as agglutinins

Precipitation:
Here as the term indicates antibodies binds to antigen and form precipitates
that are easily ingested by the phagocytes.

Complement activation: In
the previous post, we have discussed in detail the process of complement activation. Antigen-antibody complexes activate complement proteins which may
clear the pathogen either by lysis, opsonisation, inflammatory response or by
inviting phagocytes to the site of infection.